Greene County, in Iowa, sits in USDA hardiness zone 5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Expect cabbage, cranberry, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Greene County holds more than one microclimate.
Soils and elevations shift across Greene County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Greene County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Greene County — the short answer
Greene County, Iowa: USDA zone 5b, about 192 days between hard freezes, across 365K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 12
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 21
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~192
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 365K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 5b is Greene County's average, not your lot's — a low corner or a tree line moves it. Against Greene County's 192-day season, see what your own ground reads.
Heat in Greene County
Across a year, Greene County accumulates about 2,816 growing degree days above 50°F, about 72 more than the middle Iowa county — ahead of 55 of Iowa’s 99 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Greene County
Across Greene County, the ground is predominantly Mollisols, where Clarion, Nicollet, and Webster are the most extensive named soil series. The soil is generally poorly drained with a loam surface. Topsoil pH runs about 6.2–6.8, slightly acidic. Rainfall drains through hydrologic group C/D soils.
Soil order
Mollisols
Drainage
Poorly drained
Prime farmland
41%
Hydric soils
44%
Soil still varies lot by lot — soil types explained.
How the ground varies across Greene County
The USDA soil survey maps 38% of Greene County as poorly drained — but another 61% drains differently: 28% well drained, 19% somewhat poorly drained.
Clarion is the most extensive named soil at 18% of mapped acres, then Nicollet (16%) and Webster (15%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Greene County
Each reading below is measured for Greene County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Greene County are poorly drained, in hydrologic group C/D — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Greene County runs about pH 6.2–6.8, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredGreene County runs about 192 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredGreene County sits in USDA hardiness zone 5b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Greene County is in
Greene County sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Greene County
We scored all 1,086 plants against Greene County's own USDA zone 5b and its own 192-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Iowa profile.
Is it too late to plant in Greene County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 21 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
Documented around Greene County
- monarch butterfly168 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Greene County
USGS estimates 339,725 lb of Glyphosate on Greene County farmland in 2019, its largest by weight, ahead of Acetochlor (134,042 lb) and Metolachlor & Metolachlor-s (109,312 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Greene County — and how to grow with it.
We checked the federal record across Greene County — 175 documented sites across 7 of the 9 source types we track.
The most significant on record: 3 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Greene County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Greene County
Closest first, across Greene County. Listing isn't leaking, and distance isn't exposure.
- FORMER HYDRAULIC FABRICATORS FACILITYUnderground Storage Tanks · 0.6 mi
- FORMER PODLESAK MOTORSUnderground Storage Tanks · 0.8 mi
- RUSSELL CORP DBA AMERICAN ATHLETIC INCBrownfields · 0.8 mi
- NORTHRUP KING COUnderground Storage Tanks · 0.8 mi
- TRI COUNTY LUMBER MARTUnderground Storage Tanks · 0.9 mi
- SPARKY''S ONE STOP #22Underground Storage Tanks · 1.2 mi
- GREEN COUNTY MOTOR COUnderground Storage Tanks · 1.3 mi
- WEST CENTRAL COOPERATIVEUnderground Storage Tanks · 1.3 mi
- GREENE CO. JEFFERSON SHOPUnderground Storage Tanks · 1.4 mi
- CHICAGO RIVET COMPANYToxics Release Inventory · 1.4 mi
- GREENE COUNTY MAINTENANCE SHOPBrownfields · 1.4 mi
- JOE'S BODY & PAINTBrownfields · 1.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Greene County's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Greene County.
Total Sites
175
across Greene County
Risk Level
Elevated
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
across Greene County
Severity Distribution
across Greene County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Greene County, two things run higher than the national average across Greene County — Nitrate (68 sites) and Superfund (3 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Greene County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Greene County average
Your land is one point inside Greene County
Everything above resolves to Greene County as a whole — one PHZM band and one county frost record, read across 365K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at county scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better county average.
Your Lot vs the Greene County Average
Greene County Average
- ●USDA Zones 5b, averaged across Greene County
- ●One soil character for all of Greene County
- ●Frost dates read at Greene County's scale: Apr 12 to Oct 21
YOUR Parcel
- ✓Your exact zone, not Greene County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Greene County
Pull a site-specific report for your exact address in Greene County, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Greene County averages can't show:
We read public map data around Greene County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Greene County average
How we know this about Greene County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Greene County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Greene County
When does frost risk typically end in Greene County?
The last hard freeze (28°F) in Greene County typically lands around Apr 12, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 3.
How long is the growing season in Greene County?
Measured between 28°F hard freezes, Greene County sees about 192 frost-free days — roughly Apr 12 through Oct 21, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 3 to Oct 7, about 157 days.
Is the soil safe to grow vegetables in Greene County?
The federal record around Greene County is a meaningful one — 175 documented sites, mostly Underground Storage Tanks entries (73), the nearest Underground Storage Tanks record about 0.6 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
Everything above is measured at Greene County's scale — its 5b band and its 192-day season. Your yard writes its own version of Greene County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Iowa's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Greene County’s own scale
9 of the readings below were taken at Greene County's own scale — its own ~192-day span between 28°F freezes, the 3 most extensive soil series mapped here and 175 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Greene County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Greene County's own 28°F hard-freeze dates and its ~192-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Greene CountyUSDA NRCS SSURGO
- 175 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.6 miles outFederal environmental registers
- Greene County's boundary and the 364,517 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~192-day seasonGrowable Ground crop-matching engine
- Greene County sitting wholly inside the Western Corn Belt PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Greene County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Greene County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
What this page can’t tell you
- How the season shifts across Greene County — the ~192 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Greene County's 364,517 acreswhy one lot differs from the next →
- Which of those 175 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Greene Countyread your own land →